package leetcode.dynamic;

public class LCR095 {

    public int longestCommonSubsequence(String text1, String text2) {

        int[][] dp = new int[text1.length() + 1][text2.length() + 1]; //dp[i][j]代表text1的前i个字符与text2的前j个字符的两串的最大公共子序列
        //为方便写状态转移方程，下标从1开始，第0行和第0列都为0
        //最长公共子序列的状态转移方程为：
        // ① s1[i] == s2[j] dp[i][j] = dp[i-1][j-1] + 1;
        // ② s1[i] != s2[j] dp[i][j] = max(dp[i-1][j],dp[i][j-1])
        for (int i = 1; i <= text1.length(); i++) {
            for (int j = 1; j <= text2.length(); j++) {
                if (text1.charAt(i - 1) == text2.charAt(j - 1)) {
                    dp[i][j] = dp[i-1][j-1] + 1;
                } else dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]);
            }
        }
        return dp[text1.length()][text2.length()];
    }
}
